﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WinFormsApp_GetForegroundWindowTest
{
    public partial class Form1 : Form
    {
        //调用API
        [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto, ExactSpelling = true)]
        public static extern IntPtr GetForegroundWindow(); //获得本窗体的句柄
        [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SetForegroundWindow")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);//设置此窗体为活动窗体
        //定义变量,句柄类型
        public IntPtr Handle1;
        Timer timer2 = new Timer();

        public Form1()
        {
            InitializeComponent();
        }

        Form Form2;

        //在窗体加载的时候给变量赋值,即将当前窗体的句柄赋给变量
        void Form1_Load(object sender, EventArgs e)
        {
            Handle1 = this.Handle;
            timer2.Tick += new EventHandler(timer2_Tick);
            timer2.Interval = 1000;
        }

        //加载一个定时器控件,验证当前WINDOWS句柄是否和本窗体的句柄一样,如果不一样,则激活本窗体
        private void timer2_Tick(object sender, EventArgs e)
        {
            //if (Handle1 != GetForegroundWindow()) //持续使该窗体置为最前,屏蔽该行则单次置顶
            //{
            SetForegroundWindow(Handle1);
            timer2.Stop();//此处可以关掉定时器，则实现单次置顶
            //}
        }

        private void btnSetForm2ToTop_Click(object sender, EventArgs e)
        {
            if (Form2 == null) return;

            timer2.Enabled = true;
            Handle1 = Form2.Handle;
        }

        private void btn_OpenForm2_Click(object sender, EventArgs e)
        {
            Form2 = new Form();
            Form2.Text = "Form2";
            //Form2.Show();

            //调用： 
            AnimateWindow(Form2.Handle, 5000, AW_BLEND);//淡入窗体
            //Application.ExitThread();  
             
            AnimateWindow(Form2.Handle, 5000, AW_SLIDE | AW_HIDE | AW_BLEND);//淡出窗体

        }


        #region 利用API实现窗体淡入淡出特效
        //窗体淡入淡出特效
        public const Int32 AW_HOR_POSITIVE = 0x00000001; // 从左到右打开窗口
        public const Int32 AW_HOR_NEGATIVE = 0x00000002; // 从右到左打开窗口
        public const Int32 AW_VER_POSITIVE = 0x00000004;// 从上到下打开窗口
        public const Int32 AW_VER_NEGATIVE = 0x00000008;// 从下到上打开窗口
        public const Int32 AW_CENTER = 0x00000010;
        public const Int32 AW_HIDE = 0x00010000; // 在窗体卸载时若想使用本函数就得加上此常量
        public const Int32 AW_ACTIVATE = 0x00020000; //在窗体通过本函数打开后，默认情况下会失去焦点，除非加上本常量
        public const Int32 AW_SLIDE = 0x00040000;
        public const Int32 AW_BLEND = 0x00080000;// 淡入淡出效果

        [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
        public static extern bool AnimateWindow(
        IntPtr hwnd,  //  handle  to  window    
        int dwTime,  //  duration  of  animation    
        int dwFlags  //  animation  type    
        );
        #endregion



    }
}






